Heat transfer assembly for rotary regenerative preheater

ABSTRACT

Disclosed is a heat transfer assembly for a rotary regenerative preheater. The heat transfer assembly includes a plurality of heat transfer elements stacked in spaced relationship to each other in a manner such that each notch from a plurality of notches of one of the heat transfer element rests on respective flat sections from a plurality of flat sections of the adjacent heat transfer elements to configure a plurality of closed channels, each isolated from the other, wherein each of the channels has a configuration in a manner such that each of corrugation sections from a plurality of corrugation sections of one of the heat transfer elements faces respective undulation sections from a plurality of undulation sections of the adjacent heat transfer elements.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of co-pending U.S. patent applicationSer. No. 14/922,592, entitled “Heat Transfer Assembly for RotaryRegenerative Preheater,” filed on Oct. 26, 2015, which is a divisionalapplication of U.S. patent application Ser. No. 13/593,054, filed onAug. 23, 2012, now issued as U.S. Pat. No. 9,200,853. The contents ofthe aforementioned patent applications are incorporated herein byreference in their entireties and the benefits of both applications arefully claimed herein.

FIELD OF THE DISCLOSURE

The present disclosure relates to rotary regenerative air preheaters fortransfer of heat from a flue gas stream to a combustion air stream, and,more particularly, relates to heat transfer elements and assemblyconfigured thereby, for a rotary regenerative air preheater.

BACKGROUND OF THE DISCLOSURE

More often than not, rotary regenerative air preheaters are used totransfer heat from a flue gas stream exiting a furnace, to a combustionair stream incoming therein. Conventional rotary regenerative airpreheaters (hereinafter referred to as ‘preheater(s)’) includes a rotorrotatably mounted in a housing thereof. The rotor contains a heattransfer or absorbent assembly (hereinafter referred to as ‘heattransfer assembly) configured by stacking various heat transfer orabsorbent elements (hereinafter referred to as ‘heat transfer elements’)for absorbing heat from the flue gas stream, and transferring this heatto the combustion air stream. The rotor includes radial partitions ordiaphragms defining compartments there between for supporting the heattransfer assembly. Further, sector plates are provided that extendacross the upper and lower faces of the rotor to divide the preheaterinto a gas sector and one or more air sectors. The hot flue gas streamis directed through the gas sector of the preheater and transfers theheat to the heat transfer assembly within the continuously rotatingrotor. The heat transfer assembly is then rotated to the air sector(s)of the preheater. The combustion air stream directed over the heattransfer assembly is thereby heated. In other forms of regenerativepreheaters, the heat transfer assembly is stationary and the air and gasinlet and outlet hoods are rotated.

The heat transfer assembly must meet various important requirements,such as the transfer of the required quantity of heat for a given depthof the heat transfer assembly. Additionally, there may be a requirementfor low susceptibility of the heat transfer assembly to significantfouling, and furthermore easy cleaning of the heat transfer assemblywhen fouled, to protect the heat transfer elements from corrosion. Otherrequirements may include surviving of the heat transfer assembly fromwear associated with soot or ashes present in the flue gas stream andblowing there through, etc.

The preheaters, typically, employ multiple layers of different types ofthe heat transfer elements within the rotor. The rotor includes a coldend layer positioned at the flue gas stream outlet, and can also includeintermediate layers and a hot end layer positioned at the flue gasstream inlet. Typically, the hot end and intermediate layers employhighly effective heat transfer elements which are designed to providethe greatest relative energy recovery for a given depth of the heattransfer assembly. These layers of the heat transfer assemblyconventionally include heat transfer elements with open flow channelsthat are fluidically connected to each other. While these open channelheat transfer elements provide the highest heat transfer for a givenlayer depth, they allow the soot blower cleaning jets to spread ordiverge as they enter the heat transfer elements. Such divergence of thesoot blower jets greatly reduces cleaning efficiency of the heattransfer assembly and the heat transfer elements. The most significantamounts of fouling typically occur in the cold end layer due at least inpart to condensation of certain flue gas vapors. Therefore, in order toprovide heat transfer elements that allow effective and efficientcleaning by soot blower jets, the cold layer heat transfer assembly isconfigured from closed channel elements. The closed channels typicallyare straight and only open at the ends of the channels. The closedchannels form separate individual conduits for the passage of flows,with very limited potential for the mixing or transfer of flows withadjacent channels.

The closed channels configured by the combination of heat transferelements in the conventional preheaters, however, may have low heattransfer effectiveness because some of the heat transfer elements maynot have appropriate surface enhancement. Other closed channelsconfigured by the combinations of heat transfer elements may have betterheat transfer effectiveness, but due to sheets being tightly packed, maynot allow the passing of the larger soot or ash particles. Further, ifthe dimensions of such heat transfer elements were altered for looseningthe heat transfer assembly to allow the large soot or ashes to passtherefrom, the heat transfer elements may not be protected with acorrosion resistant coating, since the looseness allows the impingingsoot blower jets to induce vigorous vibrations and collisions betweenelements that damage the corrosion resistant coating.

Accordingly, there exists a need for heat transfer elements andassemblies that may effectively configure closed channel elements topreclude problems of the conventional preheaters in relation to overallheat transfer effectiveness and specifically in cold end surface, sootblowing effectiveness, passing of large soot or ash particles, cleaningof the heat transfer elements and avoiding corrosions thereof.

SUMMARY OF THE DISCLOSURE

In view of the forgoing disadvantages inherent in the prior-art, thepresent disclosure provides heat transfer elements and heat transferassemblies for a rotary regenerative preheater. Such heat transferassemblies are configured to include all advantages of the prior art,and to overcome the drawbacks inherent in the prior art and provide someadditional advantages.

An objective of the present disclosure is to provide heat transferelements having improved heat transfer capacity.

Another objective of the present disclosure is to provide heat transferelements and assemblies thereof having improved heat transfereffectiveness when configured in cold layer assemblies.

Still another objective of the present disclosure is to provide heattransfer elements and assemblies thereof for allowing improved sootblowing.

A still further objective of the present disclosure is to provide heattransfer elements and assemblies thereof that may be capable forallowing the passing of large soot or ash particles therefrom withouthaving to loosen the heat transfer assembly.

Yet another objective of the present disclosure is to provide heattransfer elements and assemblies thereof, which may be capable of beingprotected from corrosion caused by condensables present in the flue gasstream.

To achieve the above objectives, in an aspect of the present disclosure,a heat transfer assembly for a rotary regenerative preheater isprovided. The heat transfer assembly, comprising, a plurality of heattransfer elements stacked in spaced relationship to each other in amanner such that each notch from a plurality of notches on one of theheat transfer elements rests on respective flat sections from aplurality of flat sections on the adjacent heat transfer elements toconfigure a plurality of closed channels, each isolated from the other,wherein each of the channels is configured in a manner such that each ofthe corrugation sections from a plurality of corrugation sections on oneof the heat transfer elements faces the respective undulation sectionsfrom a plurality of undulation sections on the adjacent heat transferelements, and wherein each of the notches has adjacent double ridgesextending transversely from opposite sides of each of the heat transferelements to configure the spaced relationship between each of theplurality of heat transfer elements.

In an embodiment of the above aspect of the present disclosure, each ofthe plurality of heat transfer elements comprises the plurality ofundulation sections, the plurality of corrugation sections, theplurality of flat sections, and the plurality of notches, which areconfigured heat transfer elements across the width thereof, and locatedadjacent to one another.

In a further embodiment of the above aspect of the present disclosure,each of the plurality of heat transfer elements is configured to includethe plurality of undulation sections, the plurality of corrugationsections, the plurality of flat sections, and the plurality of notchesin a manner such that each of the flat sections and notches are spacedapart from each other by at least one of the undulation sections andcorrugation sections.

In a further embodiment of the above aspect of the present disclosure,the plurality of heat transfer elements comprises, a plurality of firstheat transfer elements, each of the first heat transfer elementscomprising the plurality of undulation sections and the plurality offlat sections, each of the undulation sections and the flat sections areconfigured in alternate manner across width of each of the first heattransfer elements, and a plurality of second heat transfer elements,each of the second heat transfer elements comprising the plurality ofcorrugation sections and the plurality of notches, each of thecorrugation sections and the notches are configured in alternate manneracross width of each of the second heat transfer elements.

In a further embodiment of the above aspect of the present disclosure,the plurality of heat transfer elements comprises, a plurality of firstheat transfer elements, each of the first heat transfer elementscomprising the plurality of corrugation sections and the plurality offlat sections, each of the corrugation sections and the flat sectionsare configured in alternate manner across width of each of the firstheat transfer elements, and a plurality of second heat transferelements, each of the second heat transfer elements comprising theplurality of undulation sections and the plurality of notches, each ofthe undulation sections and the notches are configured in alternatemanner across width of each of the second heat transfer elements.

In a further embodiment of the above aspect of the present disclosure,the undulation sections are configured at an angle to at least one ofthe flat section sections and the notches, and the corrugation sectionsare configured parallel to at least one of the flat section sections andthe notches.

In yet another aspect of the present disclosure, a heat transferassembly for a rotary regenerative preheater is provided. The heattransfer assembly comprising: a plurality of first heat transferelements, each of the first heat transfer elements comprising, aplurality of undulation sections and a plurality of flat sections, eachof the undulation sections and the flat sections are configured inalternate manner across width of the first heat transfer elements; and aplurality of second heat transfer elements, each of the second heattransfer elements comprising, a plurality of corrugation sections and aplurality of notches, with each of the notches having adjacent doubleridges extending transversely from opposite sides of each of the secondheat transfer elements, wherein each of the corrugation sections and thenotches are configured in alternate manner across width of the secondheat transfer elements, and wherein each of the first and second heattransfer elements are stacked in a spaced and alternate manner to othersuch that each of the notches of the second heat transfer element restson the respective flat sections of the adjacent first heat transferelement to configure a plurality of closed channels, each isolated fromthe other, wherein each of the channels is configured in a manner suchthat each of the corrugation sections of the second heat transferelements faces the respective undulation sections of the adjacent firstheat transfer elements.

A heat transfer assembly for a rotary regenerative preheater, the heattransfer assembly comprising: a plurality of first heat transferelements, each of the first heat transfer elements comprising, aplurality of corrugation sections and a plurality of flat sections, eachof the corrugation sections and the flat sections are configured inalternate manner across width of the first heat transfer elements; and aplurality of second heat transfer elements, each of the second heattransfer elements comprising a plurality of undulation sections and aplurality of notches, each notches having adjacent double ridgesextending transversely from opposite sides of each of the second heattransfer elements, wherein each of the undulation sections and thenotches are configured in alternate manner across width of the secondheat transfer elements, and wherein each of the first and second heattransfer elements are stacked in spaced and alternate manner to othersuch that each of the notches of the second heat transfer element restson the respective flat sections of the adjacent first heat transferelements to configure a plurality of closed channels, each isolated fromthe other, wherein each of the channels is configured in a manner suchthat each of the corrugation sections of the first heat transferelements faces the respective undulation sections of the adjacent secondheat transfer elements.

In another aspect of the present disclosure, a heat transfer assemblyfor a rotary regenerative preheater is provided. The heat transferassembly comprising, a plurality of heat transfer elements, each of theplurality of heat transfer elements comprising: a plurality ofundulation sections, a plurality of corrugation sections, a plurality offlat sections, and a plurality of notches, configured thereon across thewidth thereof and adjacent to one other, wherein each of the notches hasadjacent double ridges extending transversely from opposite sides ofeach of the heat transfer elements, wherein the plurality of heattransfer elements is stacked in a spaced relationship to each other in amanner such that each of the notches of one of the heat transfer elementrests on the respective flat sections of the adjacent heat transferelements to configure a plurality of closed channels, each isolated fromthe other, wherein each of the channels is configured in a manner suchthat each of corrugation sections on one of the heat transfer elementfaces the respective undulation sections of the adjacent heat transferelements.

In yet another aspect of the present disclosure, a heat transfer elementfor a heat transfer assembly of a rotary regenerative preheater isprovided. The heat transfer element comprising: a plurality ofundulation sections, a plurality of corrugation sections, a plurality offlat sections, and a plurality of notches, configured across the widthof the heat transfer element and adjacent to one another, wherein eachof the notches has adjacent double ridges extending transversely fromopposite sides of the heat transfer element.

In an embodiment of the above two aspects of the present disclosure, theheat transfer element is configured to include the plurality ofundulation sections, the plurality of corrugation sections, theplurality of flat sections, and the plurality of notches in a mannersuch that each of flat sections and notches are spaced apart from eachother by at least one of the undulation sections and the corrugationsections.

In yet another aspect of the present disclosure, a method for making aheat transfer element for a heat transfer assembly of a rotaryregenerative preheater is provided. The method comprising: configuring aplurality of undulation sections, a plurality of corrugation sections, aplurality of flat sections, and a plurality of notches having adjacentdouble ridges extending transversely from opposite sides of the heattransfer element, across the width of the heat transfer element andadjacent to one another.

In all various aspects of the present disclosure mentioned above, theundulation sections are configured at an angle to at least one of theflat section sections and the notches, and the corrugation sections areconfigured parallel to at least one of the flat section sections and thenotches.

These together with the other aspects of the present disclosure, alongwith the various features of novelty that characterized the presentdisclosure, are pointed out with particularity in the claims annexedhereto and form a part of the present disclosure. For a betterunderstanding of the present disclosure, its operating advantages, andthe specified objectives attained by its uses, reference should be madeto the accompanying drawings and descriptive material in which there areillustrated exemplary embodiments of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS OF THE DISCLOSURE

The advantages and features of the present disclosure will become betterunderstood with reference to the following detailed description andclaims taken in conjunction with the accompanying drawing, wherein likeelements are identified with like symbols, and in which:

FIG. 1 illustrates a perspective view of a rotary regenerative preheaterwhereby various heat transfer assemblies, in accordance with various andexemplary embodiments of the present disclosure are employed;

FIGS. 2A and 2B, respectively, illustrate side and top views of a heattransfer assembly, in accordance with an exemplary embodiment of thepresent disclosure;

FIGS. 3A and 3B, respectively, illustrate side and top views of a heattransfer assembly, in accordance with another exemplary embodiment ofthe present disclosure;

FIGS. 4A and 4B, respectively, illustrate side and top views of a heattransfer assembly, in accordance with yet another exemplary embodimentof the present disclosure; and

FIGS. 5A and 5B, respectively, illustrate side and top views of a heattransfer assembly, in accordance with another exemplary embodiment ofthe present disclosure.

Like reference numerals refer to like parts throughout the descriptionof several views of the drawings.

DETAILED DESCRIPTION OF THE PRESENT DISCLOSURE

For a thorough understanding of the present disclosure, reference is tobe made to the following detailed description, including the appendedclaims, in connection with the above-described drawings. Although thepresent disclosure is described in connection with exemplaryembodiments, the present disclosure is not intended to be limited to thespecific forms set forth herein. It is understood that various omissionsand substitutions of equivalents are contemplated as circumstances maysuggest or render expedient, but these are intended to cover theapplication or implementation without departing from the spirit or scopeof the claims of the present disclosure. Also, it is to be understoodthat the phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting.

The term “first,” “second” and the like, herein do not denote any order,elevation or importance, but rather are used to distinguish one elementover another. Further, the terms “a,” “an,” and “plurality” herein donot denote a limitation of quantity, but rather denote the presence ofat least one of the referenced item.

Referring to FIG. 1, a perspective view of a rotary regenerativepreheater 100 (hereinafter referred to as ‘preheater 100’) isillustrated whereby at least one of various heat transfer assemblies200, 300, 400 and 500 as shown in FIGS. 2A to 5B, in accordance withvarious exemplary embodiments of the present disclosure, may beemployed, and will be explained in conjunction with the respectivefigures in detail.

The preheater 100 includes a rotor assembly 102 rotatably mounted withina housing 104 to rotate along a rotor post 106. The rotor assembly 102is configured to include diaphragms or partitions 108 extending radiallyfrom the rotor post 106 to an outer periphery of the rotor assembly 102.Further, the partitions 108 define various compartments 110 foraccommodating various heat transfer assemblies 200, 300, 400 or 500. Thehousing 104 includes a flue gas inlet duct 112 and a flue gas outletduct 114 for the flow of heated flue gases through the preheater 100.The housing 104 further includes an air inlet duct 116 and an air outletduct 118 for the flow of combustion air through the preheater 100.Further the preheater 100 include sector plates 120 extending across thehousing 104 adjacent to lower and upper faces of the rotor assembly 102,thereby dividing the preheater 100 into an air sector 122 and a gassector 124. An arrow ‘A’ indicates the direction of a flue gas stream126 through the rotor assembly 102. The hot flue gas stream 126 enteringthrough the flue gas inlet duct 112 transfers heat to the heat transferassemblies 200, 300, 400 or 500 mounted in the compartments 110. Theheated heat transfer assemblies 200, 300, 400 or 500 are then rotated tothe air sector 122 of the preheater 100. The stored heat of the heattransfer assemblies 200, 300, 400 or 500 is then transferred to acombustion air stream 128, as indicated by the arrow ‘B,’ enteringthrough the air inlet duct 116. In this explanatory paragraph, it isunderstood that the heat of the hot flue gas stream 126 entering intopreheater 100 is utilized for heating the heat transfer assemblies 200,300, 400 or 500, which in turn heats the combustion air stream 128entering the preheater 100 for predetermined purpose.

The heat transfer assemblies 200, 300, 400, 500 will now be explained inconjunctions with FIGS. 1 to 5B. The heat transfer assemblies 200, 300,400 or 500 includes a plurality of heat transfer elements 210; 310 a,310 b; 410 a, 410 b; 510 a, 510 b; stacked in spaced relationship toeach other in a manner such that each notches 220, 320, 420, 520 of aplurality of notches 220, 320, 420, 520 of one of the heat transferelement 210; 310 a, 310 b; 410 a, 410 b; 510 a, 510 b; rests onrespective flat sections 230, 330, 430, 530 of a plurality of flatsections 230, 330, 430, 530 of the adjacent heat transfer elements 210;310 a, 310 b; 410 a, 410 b; 510 a, 510 b; to configure a plurality ofchannels 240, 340, 440, 540, each isolated from the other. Further, eachof the channels 240, 340, 440, 540 includes configuration in a mannersuch that each corrugation sections 250, 350, 450, 550 of a plurality ofcorrugation sections 250, 350, 450, 550 of one of the heat transferelement 210; 310 a, 310 b; 410 a, 410 b; 510 a, 510 b; faces respectiveundulation sections 260, 360,460, 560 of a plurality of undulationsections 260, 360,460, 560 of the adjacent heat transfer elements 210;310 a, 310 b; 410 a, 410 b; 510 a, 510 b. Further, each notches 220,320, 420, 520 having adjacent double ridges 220 a, 220 b; 320 a, 320 b;420 a, 420 b; 520 a, 520 b, extending transversely from opposite sidesof each of the heat transfer elements 210; 310 a, 310 b; 410 a, 410 b;510 a, 520 b; for configuring the spaced relationship while stacking theheat transfer elements 210; 310 a, 310 b; 410 a, 410 b; 510 a, 520 b; toconfigure the heat transfer assemblies 200, 300 400 and 500. Further,each corrugation in the corrugation sections 250, 350, 450, 550 has acorrugation crest 252, 352, 452, 552 and a corrugation trough 254, 354,454, 554 and each undulation in the undulation section 260, 360, 460,560 has an undulation crest 262, 362, 462, 562 and an undulation trough264, 364, 464, 564. For the purpose of thorough understanding of thedisclosure, each of the heat transfer assemblies 200, 300, 400 and 500will be explained in conjunction with their respective figure herein.

The heat transfer elements 210; 310 a, 310 b; 410 a, 410 b; 510 a, 520b; as mentioned are obtained by metallic sheets or plates ofpredetermined dimensions such as length, widths and thickness asutilized and suitable for making the preheater 100 that meets therequired demands of the industrial plants in which it is to beinstalled. The heat transfer elements 210; 310 a, 310 b; 410 a, 410 b;510 a, 510 b; including various configurations will be explained inconjunctions with the particular embodiments herein.

Referring now to FIGS. 2A and 2B, which respectively, illustrate sideand top views of the heat transfer assembly 200, in accordance with anexemplary embodiment of the present disclosure. The heat transferassembly 200 includes the plurality of heat transfer elements, such asthe heat transfer elements 210. Each the heat transfer elements 210includes a plurality of notches, such as the notches 220; a plurality offlat sections, such as the flat sections 230; a plurality of corrugationsections, such as the corrugation section 250; and a plurality ofundulation sections, such as the undulation sections 260, (hereinafteralso may collectively or individually referred to as ‘characteristics220, 230, 250, and 260’). Further, each notch 220 includes adjacentdouble ridges 220 a and 220 b extending transversely from opposite sidesof each of the heat transfer elements 210. All the mentioned fourcharacteristics may be configured on each of the heat transfer elements210 across the width thereof and adjacent to one another. In the presentembodiment as mentioned above, all the characteristics 220, 230, 250,and 260 are configured on one heat transfer element 210. However, suchcharacteristics 220, 230, 250, and 260, in combination of two, may beconfigured on more than one heat transfer elements and will be explainedin conjunction with FIGS. 3A to 5B. Further, FIGS. 2A to 5B depictingvarious kind of the heat transfer assemblies 200, 300, 400 and 500 areactually depicting a portion of such assemblies and may not beconsidered to be limiting as shown. Any such assemblies are formed byrepeatedly applying characteristics 220, 230, 250, and 260.

In one embodiment of the present disclosure, the notches 220 and theflat sections 230 are spaced apart, from at least one of the corrugationsections 250 and the undulation sections 260 on each of the heattransfer elements 210. In an exemplary embodiment, as shown in FIGS. 2Aand 2B, the characteristics 220, 230, 250, and 260 are configured in thefollowing order, such as the flat section 230, the undulation section260, the notches 220 and the corrugation sections 250. However, withoutdeparting from the scope of the present disclosure the characteristics220, 230, 250, and 260 may be configured in any order to obtain thechannels 240, depending upon the industrial requirements. According tothis embodiment of the present disclosure, all mentioned characteristics220, 230, 250, and 260 are configured on each of the single heattransfer elements 210, in its most likely form, by single rollmanufacturing process, utilizing a single set of rollers. Subsequent toconfiguring the characteristics 220, 230, 250, and 260, each such heattransfer elements or sheets 210 may be coated with a suitable coating,such as porcelain enamel, which makes the heat transfer elements orsheets 210 slight thicker and also prevent the metallic sheet substratesfrom directly being in contact with the flue gas, thereby preventingcorrosion from the effects of soot, ashes or condensable vapors withinthat stream.

The characteristics 220, 230, 250, and 260 are configured on each of theheat transfer elements 210 in a specific manner. In one embodiment, eachundulation of the undulation sections 260 is configured at an angle toat least one of the flat sections 230 and the notches 220. For example,as shown in FIG. 2B, the undulations 260 are configured at an angle ‘Φ’with respect to the flat section 230, or may be configured at an angle‘α’ with respect to the notches 220. In one scope, the angles ‘Φ’ and‘α’ may be of same degrees, and in another scope said angles may bedifferent, depending upon the requirements. Further, the characteristicssuch as the corrugation sections 250 are also configured in a particularmanner with respect to the at least one of the notches 220 and the flatsections 230. In one embodiment as shown in FIG. 2B, the corrugationsections 250 are configured parallel to at least one of the notches 220and the flat sections 230. From the above writer descriptions about thecharacteristics 220, 230, 250, and 260, it may be clearly evident thatthe undulations or undulation sections 260 extend angularly with respectto the notches 220 or the flat sections 230, and that the corrugationsor the corrugation sections 250 are configured parallel with respect tothe notches 220 or the flat sections 230. The terms such as‘corrugations’ or ‘corrugation sections;’ ‘flats’ or ‘flat sections;’and ‘undulations’ or ‘undulation sections’ are alternatively andinterchangeably used throughout the description and may be considered assame.

For configuring the channels 240 according to the present embodiment asmentioned above, various heat transfer elements 210 are stacked inspaced relationship to each other. The stacking thereof are in such amanner that each of the notches 220 of one of the heat transfer element210 rests on the flats 230 of the adjacent heat transfer element 210.For example, as shown in FIG. 2A, the notch 220 of the top heat transferelement 210 rests on the flat 230 of the adjacent lower heat transferelement 210, similarly, the notch 220 of the lower heat transfer element210 rests on the flat 230 of the adjacent top heat transfer element 210,thereby configuring the channel 240. Similarly, various channels 240 areconfigured across the heat transfer elements 210 when various such heattransfer elements 210 are stacked together. The stacking of the heattransfer elements 210 may be tight enough to avoid looseness and stillallow the substantially larger size soot or ash particles to passtherefrom.

The channels 240, as formed, include a particular configuration toachieve above objectives, in accordance with the various embodiments ofthe present disclosure. The channels 240 are isolated from one anotherdue to the contact between the notches 220 and the flats 230,(hereinafter may also be selectively referred to as the ‘closed channels240’), and may be generally straight and opened across the ends thereof.The closed channels 240 encourage the flow of the fluids, such as thosefrom impinging soot blower jets, to pass straightly through withoutspreading or diverging across the width of the heat transfer elements210. Further, while stacking various heat transfer elements 210, asuitable spacing are achieved between the two consecutive heat transferelements 210 due to the presence of the notches 220, and moreparticularly, due to the ridges 220 a and 220 b that rests on therespective flats 230 of the adjacent heat transfer elements 220. This isdue to the fact that the ridges 220 a and 220 b of the notches 220 areconfigured at such measured predetermined heights that enable therequired spacing between the consecutive heat transfer elements 210.Such required spacing between the two consecutive heat transfer elements210 results in a suitable depth of the closed channels 240 tosubstantially allow the passing of the large soot or ash particlestherefrom, which in turn prevents the plugging or blocking of the heattransfer assembly 200, and accordingly of the preheater 100. Forexample, the closed channels 240 of the present disclosure may becapable of passing the soot or ash particles of size up to about 9/32inches, approximately about 7 millimeters, effectively. However, withoutdeparting from the scope of the present disclosure, the heat transferassembly 200 may be configured to enable passing of the even larger sizeof the soot or ash particles.

As cited above, in a conventional heat transfer assembly mounted in somepreheaters are generally loosely stacked elements for allowing thepassing of larger soot or ash particles therefrom. Such loosely stackedheat transfer assemblies result in the collisions of the heat transferelements with each other due to vigorous vibrations caused by impingingsoot blower jets. The present disclosure may be capable of precludingsuch problems due to the notches 220 and flats 230 being in closeconfiguration or resting on each other and still enabling to pass thelarge sized soot or ash particles from the closed channels due to thesize of ridges 220 a and 220 b being sufficiently high. Specifically, asmentioned above, subsequent to making the heat transfer elements 210with the mentioned characteristics, the heat transfer elements 210 arebeing coated with a suitable coating. Such coatings are prone to damagein the loosely stacked assemblies due to collision of the heat transferelements 210 during soot blowing, which may generally not be the casewith the present disclosure.

Further, each of the channels 240 configured in the heat transferassembly 200, the alignments of the corrugations 250 and undulations 260on the adjacent heat transfer plates 210 are in such a manner that theyfaces each other. In one embodiment of the present disclosure, there maybe a clearance gap of substantial distance, and in another embodimentthere may be clearance gap of about null, between the corrugations 250and the adjacent undulation 260 of two consecutive heat transferelements 210 stacked for configuring the channels 240. Such aconfiguration of the channels 240 is capable of increasing heat transfereffectiveness exceeding the current cold end surfaces, in overall heattransfer effectiveness of the preheater 100.

Referring now to FIGS. 3A to 4B, wherein heat transfer assemblies, suchas the heat transfer assemblies 300 and 400 are illustrated inaccordance with another embodiment of the present disclosure.Specifically, referring to FIGS. 3A and 3B, the heat transfer assembly300 includes the plurality of heat transfer elements, such as theplurality of first heat transfer elements 310 a and the plurality of thesecond heat transfer elements 310 b. Each of the first heat transferelements 310 a includes a plurality of undulation sections, such as theundulation sections 360, and the plurality of flat sections, such as theflat sections 330. Each of the undulation sections 360 and the flatsections 330 are configured in alternate manner across width of each ofthe first heat transfer elements 310 a. Each of the undulation troughs364 extend toward the second heat transfer element 310 b. Further, eachof the second heat transfer elements 310 b includes a plurality ofcorrugation sections, such as the corrugation sections 350, and theplurality of notches, such as the notches 320. Each of the corrugationsections 350 and the notches 320 are configured in alternate manneracross width of each of the second heat transfer elements 310 b. Each ofthe corrugation crests 352 extend toward the first heat transfer element310 a.

In this embodiment, as mentioned and illustrated, two characteristicsout of 320, 330, 350, and 360 are configured per heat transfer elements310 a, 310 b instead of one heat transfer element, such as in the heattransfer elements 210. To configure the channels, such as the channels340, the first and second heat transfer elements 310 a, 310 b, arealternately stacked in such a manner that the notches 320 of the secondheat transfer element 310 b rest on the flat section 330 of the adjacentfirst heat transfer elements 310 a. The channels 340 have similarconfiguration as of the channels 240, and the explanation thereof isexcluded herein for the sake of brevity. The stacking of the pluralityof first and second heat transfer elements 310 a and 310 b are in thespaced relationship from each other, and also in tightly packed manneras explained above, due the suitable heights of the ridges 320 a and 320b of the notches 320 configured on each of the second heat transferelements 310 b.

The notches 320, flats 330, corrugations 350, and undulations 360, areconfigured on the respective heat transfer elements 310 a and 310 b in aspecific manner. In one embodiment, undulations 260 are configured at anangle to the flats 330 on the first heat transfer element 310 a. Forexample, as shown in FIG. 3B, the undulations 360 are configured at anangle ‘Φ’ with respect to the flats 330. Further, the corrugations 350are also configured in a particular manner with respect to the notches320 on the second heat transfer elements 310 b. In one embodiment asshown in FIG. 3B, the corrugation sections 350 are configured parallelto the notches 320. From the above written descriptions it may beclearly evident that the undulations 360 extend angularly with respectto the flat sections 330 on the first heat transfer elements 310 a, andthat the corrugations 350 are configured parallelly with respect to thenotches 320 on the second heat transfer elements 310 b.

Referring now to FIGS. 4A and 4B, the heat transfer assembly 400 isillustrated. The heat transfer assembly 400 is substantially similar tothe heat transfer assembly 300. Similar to the heat transfer assembly300, the heat transfer assembly 400 also includes the plurality of heattransfer elements, such as the plurality of first heat transfer elements410 a and the plurality of the second heat transfer elements 410 b. Eachof the first heat transfer elements 410 a includes a plurality ofundulation sections, such as the undulation sections 460, and theplurality of flat sections, such as the flat sections 430. Each of theundulation sections 460 and the flat sections 430 are configured inalternate manner across width of each of the first heat transferelements 410 a. Each of the undulation troughs 464 extend toward thesecond heat transfer element 410 b. Further, each of the second heattransfer elements 410 b includes a plurality of corrugation sections,such as the corrugation sections 450, and the plurality of notches, suchas the notches 420. Each of the corrugation sections 450 and the notches420 are configured in alternate manner across width of each of thesecond heat transfer elements 410 b. Each of the corrugation crests 452extend toward the first heat transfer element 410 a. The fact ofalteration between the heat transfer assemblies 300 and 400 may bebetween the configurations of the corrugations. The corrugations 450 maybe more curve and circular in shape, and compact, while the corrugations350 may be edgy and less compact. The curve and compactness of thecorrugations 450 may be capable of having comparatively betterefficiency over all of the heat transfer assembly 400. The channels 440are configured by alternatively stacking the first and second heattransfer elements 410 a and 410 b, as in the case of the heat transferassembly 300. The detailed explanation of the same is excluded hereinfor the sake of brevity. The notches 420, flats 430, corrugations 450,and undulations 460, are configured on the respective heat transferelements 410 a and 410 b in a similar manner as explained above withrespect to FIGS. 3A and 3B. For example, as shown in FIG. 4B, theundulations 460 are configured at an angle ‘Φ’ with respect to the flatsection 430 on the first heat transfer element 410 a. Further, thecorrugation sections 450 are configured parallel to the notches 420 onthe second heat transfer element 410 b. When all of the corrugations inthe corrugation sections 450 have an angular or edgy shape, at least aportion of an undulation rough 464 in an undulation section 460 that isbetween two flay sections 430 touches at least a portion of onecorrugation crest 452 in a corrugation section 450 that is in betweentwo notches 420 such that there is no gap between the touching portionsof the undulation trough 464 and the corrugation crest 452.

Referring now to FIGS. 5A and 5B, a heat transfer assembly, such as theheat transfer assembly 500 is illustrated in accordance with anotherembodiment of the present disclosure. The heat transfer assembly 500includes the plurality of heat transfer elements, such as the pluralityof first heat transfer elements 510 a and the plurality of the secondheat transfer elements 510 b. Each of the first heat transfer elements510 a includes a plurality of flat sections, such as the flat sections530, and a plurality of corrugation sections, such as the corrugationsections 550. Each of the flat sections 530 and the corrugation sections550 are configured in alternate manner across width of each of the firstheat transfer elements 510 a. Each of the corrugation troughs 554 extendtoward the second heat transfer element 510 b. Further, each of thesecond heat transfer elements 510 b includes a plurality of notches,such as the notches 520, and a plurality of undulation sections, such asthe undulation sections 560. Each of the undulation sections 560 and thenotches 520 are configured in alternate manner across width of each ofthe second heat transfer elements 510 b. Each of the undulation crests562 extend toward the first heat transfer element 510 a. At least aportion of a corrugation trough 554 in a corrugation section 550 betweentwo flat sections 530 touches at least a portion of an undulation crest562 in an undulation section 560 between two notches 520 such that thereis no gap between the touch portions of the corrugation rough 554 andthe undulation crest 562.

In this embodiment similar to the above embodiments as depicted in FIGS.3A to 4B, two characteristics out of 520, 530, 550, and 560 areconfigured per heat transfer elements 510 a, 510 b instead of one heattransfer element, such as the heat transfer elements 210 depicted inFIGS. 2A and 2B. To configure the channels, such as the channels 540,the first and second heat transfer elements 510 a, 510 b, arealternately stacked in such a manner that the notches 520 of the secondheat transfer element 510 b rest on the flat section 530 of the adjacentfirst heat transfer elements 510 a. The channels 540 have the similarconfiguration as of the channels 240, 340, and 440, and explanationthereof is excluded herein for the sake of brevity. The stacking of theplurality of the first and second heat transfer elements 510 a and 510 bare in the spaced relationship from each other and also in tightlypacked manner as explained above, due the suitable heights of the ridges520 a and 520 b of the notches 520 configured on each second heattransfer elements 510 b.

Further, the notches 520, flats 530, corrugations 550, and undulations560, are configured on the respective heat transfer elements 510 a and510 b. The corrugation sections 550 are configured in a particularmanner with respect to the flats 530 on each of the first heat transferelement 510 a. Specifically, the corrugation sections 550 are configuredparallel to the notches 520. Further, the undulation sections 560 areconfigured at an angle to the notches 520 on the second heat transferelements 510 b. For example, the undulations 560 are configured at anangle ‘Φ’ with respect to the notches flat section 330.

Further, the configuration of the channels 340, 440 and 540 of the aboveembodiments are all similar to the channels 240, and includes all theadvantages features as explained in conjunction to the channels 240 inthe scope thereof. Similarly, the heat transfer assemblies 300, 400 and500 also includes all advantageous features explained in the conjunctionwith the heat transfer assembly 200, and excluded herein for the sake ofbrevity. Further according to various embodiments of the presentdisclosure, there may be a clearance gap of substantial distance, orthere may be clearance gap of about null, between the corrugations 350,450, 550 and the adjacent undulation 360, 460, 560 of two consecutiveheat transfer elements 310 a and 310 b; 410 a and 420 b; 520 a and 529b, stacked for respectively configuring the channels 340, 450 and 550.

The heat transfer elements 210; 310 a, 310 b; 410 a, 410 b; 510 a, 510 band the respective heat transfer assemblies 200, 300, 400 or 500, aregenerally described herein as per a bi-sector type air preheater.However, the disclosure extends to include configuration and stacking ofthe various heat transfer elements for other kinds of air preheater suchas a tri-sector or quad-sector type air preheaters, and explanationthereof are excluded herein for the sake of brevity. In general, thepreheater 100 may be any of the bi-sector, tri-sector or quad-sectortype air preheaters and configuration or stacking of the various heattransfer elements of the disclosure may be done as per the requirementsof the kind of the air preheaters.

The heat transfer elements 210; 310 a, 310 b; 410 a, 410 b; 510 a, 510 band the heat transfer assemblies 200, 300, 400 or 500, respectively,configured thereby utilized in conjunction with the preheater 100 in anindustrial plant offer the following advantages, apart from mentionedabove. The present disclosure is advantageous in providing improved heattransfer effectiveness overall and specifically for the cold end surfaceof the air preheaters. Further, the heat transfer assemblies of thepresent disclosure are advantageous in providing improved soot blowingeffectiveness. Furthermore, the heat transfer elements and assembliesthereof are tightly packed and still capable for allowing the passage oflarge soot or ash particles therefrom without having to loosen the heattransfer assemblies. Due to the tightly packed assemblies, whichpreclude collision of the heat transfer elements, the coating ofporcelain enamel and the like on the heat transfer elements do not getdestroyed, thereby reduces the chances of corrosions of the heattransfer elements. Moreover, the assemblies are also capable ofpermitting soot blower energy to penetrate through the heat transfersurface with sufficient energy to clean the heat transfer elementspositioned further from the soot blowing equipment, which also cleansthe coatings for corrosion protection, and to facilitate ash or sootdeposit removal. Further, the closed channel feature may be suitable forapplications such DeNOx application, where ammonium bisulfate depositsmay form in the heat transfer assemblies. The assemblies of the presentdisclosure is capable of preserving soot blowing energy, therebyenabling the heat transfer elements to be effective for the use of DeNOxapplication. Further, the disclosed heat transfer elements 210; 310 a,310 b; 410 a, 410 b; 510 a, 510 b may also be used in gas-to-gas heatexchangers that are generally used for stack gas reheat.

The foregoing descriptions of specific embodiments of the presentdisclosure have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit thepresent disclosure to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteaching. The embodiments were chosen and described in order to bestexplain the principles of the present disclosure and its practicalapplication, to thereby enable others skilled in the art to best utilizethe present disclosure and various embodiments with variousmodifications as are suited to the particular use contemplated. It isunderstood that various omission and substitutions of equivalents arecontemplated as circumstance may suggest or render expedient, but suchare intended to cover the application or implementation withoutdeparting from the spirit or scope of the claims of the presentdisclosure.

What is claimed is:
 1. A heat transfer assembly for a rotaryregenerative preheater, the heat transfer assembly comprising: aplurality of heat transfer elements stacked in spaced relationship toeach other in a manner such that each notch from a plurality of notchesfrom one of the heat transfer elements rests on respective flat sectionsfrom a plurality of flat sections from the adjacent heat transferelements to configure a plurality of closed channels, each isolated fromthe other, wherein each of the channels has a configuration in a mannersuch that each corrugation section from a plurality of corrugationsections from one of the heat transfer elements faces respectiveundulation sections from a plurality of undulation sections from theadjacent heat transfer elements, and wherein each of the notches hasadjacent double ridges extending transversely from opposite sides ofeach of the heat transfer elements to configure the spaced relationshipbetween each of the plurality of heat transfer elements, each undulationin the undulation sections are configured at an angle to at least one ofthe flat sections and the notches over an entire length of the heattransfer element, the angle of the undulation to a flat section is afirst angle and the angle of the undulation to a notch is a secondangle, wherein the first angle and the second angle are different orequal, and the corrugation sections are configured parallel to at leastone of the flat sections and the notches over the entire length of theheat transfer element, wherein the plurality of heat transfer elementscomprises: a plurality of first heat transfer elements, each of thefirst heat transfer elements comprising the plurality of undulationsections and the plurality of flat sections, each of the undulationsections and the flat sections are configured in an alternating manneracross width of each of the first heat transfer elements, the undulationsections being configured at an angle to the flat sections over theentire length of each of the first heat transfer elements; and aplurality of second heat transfer elements, each of the second heattransfer elements comprising the plurality of corrugation sections andthe plurality of notches, each of the corrugation sections and thenotches are configured in an alternating manner across width of each ofthe second heat transfer elements, the corrugation sections beingconfigured parallel to the notches over the entire length of each of thesecond heat transfer elements, wherein each undulation of the undulationsections comprises an undulation crest and an undulation trough and eachcorrugation of the corrugation sections comprise a corrugation crest anda corrugation trough, each of the undulation troughs extends toward thesecond heat transfer element and each of the corrugation crests extendstoward the first heat transfer element and creating a gap between theundulation section of the first heat transfer element and thecorrugation section of the second heat transfer element, and whereineach corrugation trough comprises a curved shape, the curved shape beingthe same for each corrugation trough and each corrugation crestcomprises the curved shape, the curved shape being the same for eachcorrugation crest.
 2. The heat transfer assembly according to claim 1,wherein each corrugation has a crest-to-trough amplitude.
 3. The heattransfer assembly according to claim 2, wherein each of thecrest-to-trough amplitudes is identical.
 4. A heat transfer assembly fora rotary regenerative preheater, the heat transfer assembly comprising:a plurality of first heat transfer elements, each of the first heattransfer elements comprising a plurality of undulation sections and aplurality of flat sections, each of the undulation sections and the flatsections are configured in an alternating manner across width of each ofthe first heat transfer elements, the undulation sections beingconfigured at an angle to the flat sections over the entire length ofeach of the first heat transfer elements, and a plurality of second heattransfer elements, each of the second heat transfer elements comprisinga plurality of corrugation sections and a plurality of notches, each ofthe notches has adjacent double ridges extending transversely fromopposite sides of each of the second heat transfer elements, whereineach of the corrugation sections and the notches are configured in analternating manner across width of each of the second heat transferelements, the corrugation sections being configured parallel to thenotches over the entire length of each of the second heat transferelements; wherein each undulation of the undulation sections comprisesan undulation crest and an undulation trough and each corrugation of thecorrugation sections comprise a corrugation crest and a corrugationtrough, each of the undulation troughs extends toward the second heattransfer element and each of the corrugation crests extends toward thefirst heat transfer element and creating a gap between the undulationsection of the first heat transfer element and the corrugation sectionof the second heat transfer element, wherein each corrugation troughcomprises a curved shape, the curved shape being the same for eachcorrugation trough and each corrugation crest comprises the curvedshape, the curved shape being the same for each corrugation crest, andwherein each of the first and second heat transfer elements are stackedin spaced and alternating manner to each other such that each of thenotches of the second heat transfer element rests on the respective flatsections of the adjacent first heat transfer element to configure aplurality of closed channels, each isolated from the other, wherein eachof the channels has a configuration in a manner such that each ofcorrugation sections of one of the first heat transfer elements and thesecond heat transfer elements faces the respective undulation sectionsof the other of an adjacent one of the first heat transfer elements andthe second heat transfer elements.
 5. The heat transfer assemblyaccording to claim 4, wherein each corrugation has a crest-to-troughamplitude.
 6. The heat transfer assembly according to claim 5, whereineach of the crest-to-trough amplitudes is identical.
 7. A heat transferassembly for a rotary regenerative preheater, the heat transfer assemblycomprising: a plurality of heat transfer elements stacked in spacedrelationship to each other in a manner such that each notch from aplurality of notches from one of the heat transfer elements rests onrespective flat sections from a plurality of flat sections from theadjacent heat transfer elements to configure a plurality of closedchannels, each isolated from the other, wherein each of the channels hasa configuration in a manner such that each corrugation section from aplurality of corrugation sections from one of the heat transfer elementsfaces respective undulation sections from a plurality of undulationsections from the adjacent heat transfer elements, and wherein each ofthe notches has adjacent double ridges extending transversely fromopposite sides of each of the heat transfer elements to configure thespaced relationship between each of the plurality of heat transferelements, each undulation in the undulation sections are configured atan angle to at least one of the flat sections and the notches over anentire length of the heat transfer element, the angle of the undulationto a flat section is a first angle and the angle of the undulation to anotch is a second angle, wherein the first angle and the second angleare different or equal, and the corrugation sections are configuredparallel to at least one of the flat sections and the notches over theentire length of the heat transfer element, wherein the plurality ofheat transfer elements comprises: a plurality of first heat transferelements, each of the first heat transfer elements comprising theplurality of corrugation sections and the plurality of flat sections,each of the corrugation sections and the flat sections are configured inan alternating manner across width of each of the first heat transferelements, the corrugation sections being configured parallel to the flatsections over the entire length of each the first heat transferelements; and a plurality of second heat transfer elements, each of thesecond heat transfer elements comprising the plurality of undulationsections and the plurality of notches, each of the notches has adjacentdouble ridges extending transversely from opposite sides of each of thesecond heat transfer elements, each of the undulation sections and thenotches are configured in an alternating manner across width of each ofthe second heat transfer elements, the undulation sections beingconfigured at an angle to the notches over the entire length of each ofthe second heat transfer elements, wherein each corrugation of thecorrugation sections comprises a corrugation crest and a corrugationtrough and each undulation of the undulation sections comprises anundulation crest and an undulation trough, each of the corrugationtroughs extending toward the second heat transfer element and each ofthe undulation crests extending toward the first heat transfer element,and further wherein at least a portion of a corrugation trough in acorrugation section between two flat sections touches at least a portionof an undulation crest in an undulation section between two notches suchthat there is no gap between the touching portions of the corrugationtrough and undulation crest.